Synchrorotor



E. G. THOMAS.

I SYNCHRORQTOR. APPLICATION HLED JUNE 12,1916. RENEWED AUG. 28. i918.

Patented June 14,1921.

WITNESSES 'mvzNToR UNITED PATENT OFFICE.

' JiDwARD G. THOMAS, or r mmars; ILLINOIS.

" srncnnonoron.

p irinof L tter' 'laten [Patented June 14; 1921.

Application filed June 12,-1916,'S'erial 1104103208. ReneWedAugi StIZS, 1918. Serial No. 251,837.

To all "10710772, it may concern Be it known that I, EDW RD G. THOMAS, of Springfield, county of SangamonpState of Illinoisshave invented and produced oer tain new and useful Improvements in Synchrorotors, of which the following is a specification, reference being had to the accompanying drawings, which form a part thereof. r I

My invention is intended toprovide an improved apparatus by which the move-' ments of a mechanical"device, such as a ro-' tatin'g' shaft may be controlled by and made:

synchronouspwith the periodic movements of another device,-:t'or example, a pendulum or another rotating shaft. For convenience the former device and its operatingimech anism may be termed the governeddevice,

and the lattertheFcontrOlling device. This invention is animprovement on the invention disclosed and claimed in applicants U. S. Patent #1045909 and maybe applied to similaruses. i

The controlling device may consist of any assemblage of parts havlng a PBI'L'OCllC rotary 0rj,reciprocating motion suchas a clock pendulum, wh le the governed device may be described in a general way as com-' pr1smg- A rotating member which is drivenv by power from an outside source, a device for adjusting the speed of the driving mechanism so that it shall tend to drive themtating member at a speedslightly'below the desired rate or at a speed slightly above this rate, means for selecting one specd'or the other of the driving mechanism in accord-' ance withthe angular position of the rotating member at the time of such selection 40 and a ling device for causing such aselection to periodically occur. If the rotating member shall have turned through a less are than is represented'byits desired rateyof rotation, the greater speed of the driving mechanism the next period. Thus the rotating member will alternately bev accelerated and retarded in order that its total revolutions shall correspond exactly to those represented by the oaratus connected with the control desired rate eXcept for the minute differences which will occur between the periodic selections. '1 p While the apparatus may be made to accomplishthe.results desired by the use of mechanicalparts, electricity. can be used to advantage in simplifying the construction of: the vmechanism and/the specific formto 'wliich' 'the "greater part of the following description 2113131163 is that in which the con ling dcvi ce' consists ofa clock 1 arranged to momentarily close-anelectric circuit at each swing oi? its penduluml2; At the lower. end

of the clock case is located a block 3 having a rccessinits upper-surface containing a little mercury lofsuch volume that the meniscus formed byits upper surface will project above block 3 'andinto the path of pendulum 2 as it swings to and fro, so that the lower end of the pendulum-touches the mercury, at every swing, thereby momentarily" closing an electric circuit, of which one wire is electrically connected to the pendulumQ and the other touches the mercury 4. {This circuit controller is entirely diagrammatical in character, is not a part of this invention, and may be replaced by any other "form of mechanism which will serve to periodically open and close an electric circuit.

The governed device comprises, according to'the construction shown, an electric motor 11 having an extended shaft 12 suitably journaled in afsupport 13 se'cured'to the base of the machine '14; and having firmly secured to it a balancewheel 15. Upon the shaft 12a fly wheel 100 is-rotativelyinount- 'ed and .one'end of a torsion spring 16 encircling "the shaft is fastened to the fly wheel. The other end of spring 16 is les tened to a collar 16 tightly secured to shaft 12 by a set screw, the spring thus forming an elastic (:lriving connection between shaft 12 and fly wheel 100. To the fiy wheel 100 is secured in any suitable manner the mech anism to be synchronized herein diagrammatically represented by bevel gear 17, bevel gears 18 and 19, rotatively mounted in gear 21, bevel gear 20 and commutator 22 rigidly secured together and rotatively mounted on shaft 12. Gear 21 is also mounted'on shaft 12 so as to be able to turn freely thereon. Bevel gears 17, 18, 19, and 20 and their mounting gear 21 constitute a differential gear of which the purpose will be disclosed later.

Two speed regulating devices 23 and 24 are mounted on balance wheel 15. Device 23 consists of a weight 25 pivoted at 26, and having a relatively long arm 27 extending inwardly and adapted. to move between a stop 29 and a contact screw tapped into an insulating block 31. A tension spring 32 tends to hold the arm 27 against stop 29 and to resist any tendency of the arm to move toward the contact screw caused by the centrifugal force of the weight 25 when the apparatus is in motion. Below the speed at which the device is set the force of the spring will overcome the centrifugal fo 'ce of the weight and hold the arm away from the contact screw 30, while above this speed the centrifugal force of the weight will preponderate and cause the arm to make contact with screw 30.

Speed. regulating device 24% is similarly constructed of weight 25 pivoted at 26, arm 27, stop 29, contact screw 30 mounted in insulating block 31 and spring 32'.

Contact screw 30 is connected by a wire 33 with a contact ring 34 mounted on an insulating ring 35 on shaft 12, and contact screw 30 is connected with contact ring 3% on insulating ring 35, by a wire 33. Con tact brushes 75 and 75 are mounted on an insulating block so as to register with and touch the contact rings 3 and 34.

The motor 11 is direct current, shunt wound and receives current from any extraneous source by means of the wires marked Line. The field and armature of the motor are in multiple. In the field circuit is placed a resistance 40, which may be shortcircuited by the closing of a relay switch 41, which will allow the field current to pass around the resistance 10, through wires 42 and as. Since the speed of the motor may be varied by varying the strength of its field, the motor will run faster when the relay is open than when it is closed, since the resistance of the field circuit will be greater when the resistance is in circuit than when it is out out by the closing of the relay. The motor and resistance should be so designed and related that the motor will run at a speed somewhat under the lowest speed at which either of the speed regulating devices is set to act, when its field circuit is shunted around resistance 40; and at a speed somewhat higher than the highest speed at which either of the speed regulating devices is set to act, when resistance 40 is in the motor field circuit. A five per cent. difference between the low speed of the motor and its high speed is considered a desirable amount.

The motor speed will not, however, reach these extremes since the governor arm 27 will make contact with contact point 30 before the motor can reach the speed at which it would run were resistance 40 permanently placed in the motor field circuit, thereby making the motor slow down by causing resistance 40 to. be out out of the motor field circuit by relay tl; and the governor arm at which the speed regulating device is set a to act should be very little and will depend on the delicacy of the apparatus.

It will be obvious that the motor is not governed in reference to the desired uniform speed of the synchrorotor as a whole but in reference to the speed at which the particular speed regulating device in use at the moment is set. The two speeds cor responding to the two speed regulating devices are the only speeds at which the motor will tend to run and neither of these speeds is that of the synchrorotor as a whole. One is greater and the other is less.

The circuit operating relay 4:1 includes wires 44-. from the coil of the relay, battery 45, wire 46 to a ground -17 on the base 14:, thence to fly wheel 15, to the speed governing-device 23 or 21, wire :33 or 35, contact ring 34ror 3st, to contact brush or 75, wire 77 or 77, to the contact point 76 or 76 of a double relay 41-8, thence to relay lever 49, and through wire 50 to the coil of relay 411. according to the position of relay lever 19 against one contact point 76 or 76, speed regulating device 23 or device 2 1 will be in the circuit of relay #11 and will regulate motor 11 to run close to the particular speed for which the speed regulating device is designed, by opening or closing the relay circuit as the balance wheel varies in speed, putting resistance in the motor field when a higher speed is needed and cutting it out when a lower speed is desired, to the end that the average motor speed shall ap- It will be seen that earner proximate closely the speed at which the speed regulating device is set to act.

The purpose of the double relay 48 is to switch into circuit the particular speed regulating device 23 or 24 made necessary by the angular position of fly wheel .100 at the moment that the circuit is closed by the pendulum 2 touching mercury bubble 4 and in order that double relay 48 shall make the proper selection a contact block 78 is mounted 011 the periphery of the fly wheel 100 in such a position as to make contact in each rotation with two brushes 51 and 52 mounted on an insulating block 79 attached to the base of the machine. The contact points of brushes 51 and 52 are not side by side, but

are located in such angular relation to the fly wheel that one brush 52, will be just passing from contact with block 78 as the other brush 51, makes contact with it. Brushes 51 and 52 are connected by wires 53 and 53 to coils 54 and 54 of relay 48 and the circuit continues through common wire 55 to the clock operated circuit breaker shown diagrammatically by the mercury bubble 4 in the path of pendulum 2 and thence through wire 59- to the battery 45 and wire 46 to the base 14.

The operation of the mechanism illustrated is as follows: We will assume that the clock movement selected is one beating seconds and therefore adapted to close and open the circuit of the double relay 60 times per minute and that the speed desired for the governed mechanism is 69 revolutions per minute. it is then assumed that speed regulating mechanism 23 be carefully adjusted to act at a speed of 61 revolutions per minute and speed regulating device 24 be set at 59 revolutions. The apparatus may then be started up and will be brought to a speed of 61 revolutions if the lever of the double relay happens to be in contact with contact 76 or 59 revolutions it touching with 76'. The apparatus will then in a few revolutions reach a position such that one of the contact brushes 51 or 52 will be in Contact with contact block 7 8 at the moment when the circuit of the double relay is closed by the clock-operated circuit breaker.

lVe will assume that the mechanism is running at 61 revolutions per minute. Then contact block 78 will come into contact first with brush 52-at the moment when the clock operated circuit breaker makes contact. As lever 49 is already in contact with contact point 76, which is connected with the fast speed regulating mechanism, no change will result and the synchrorotor will continue to run at fil revolutions and will gain in angular motion till contact block 7 8 is no longer in contact with brush 52 but is in contact with brush 51 at the moment when the circuit is closed by the clock operated circuit breaker. WVhen this occurs coil 54 of the double relay 48 will bemomentarily energized and relay lever 49 will be attracted and will be pulled against contact point 76 The slower governor 24 will now be in circuit with the relay 41 and the speed of the motor will accordingly be reduced rapidly to 59 revolutions. The fly wheel will at first have the higher rotative speed corresponding to the faster governor, but will be retarded by the slower motion of the motor, though a part of the dilference in speed will be absorbed temporarily by the spring 16 since the inertia or" fly wheel 100 will have to be overcome. It the reduction of the angular motion of fly wheel 100 during the period before the circuit of relay 48 is again closed by the clock is so great that contact block 78 is in contact with brush 52 when the clock closes the circuit, coil 54 of relay 48 will be energized and will pull lever 49 from contact )oint 76 to contact point 7 6 and thus switc the circuit of speed governing relay '41 to the faster speed regulating mechanism Then during the next period or" one second the motor will run at 61 revolutions and the fly wheel will be accelerated. It, however, the reduction in the angular motion of fly wheel 100 is not great enough to bring contact block 78 under brush 52 at the moment of the closing of the double relay circuit by the clock. but instead brush 51 is in contact, relay coil 54 will be energized and will retain lever 49 against contact point 76. The motor will then continue to run at 59 revolutions and the fly wheel 100 still further retarded. An ideal condition will be reached when the speed regulating devices are alternately in circuit in succeeding periods. In any event v the inertia of the motor, the elasticity f the spring 16, and the inertia oi the fly wheel 109, all will tend to rduce the actual acceleration or, retardation of the fly wheel, which will occupy within close limits a median position in reference to brushes 51 and 52 at the moment of the closing of the circuit by the clock-operated circuit breaker.

By a suitable relation between the inertia of the fly wheel and synchronized mechanism and the strength of the driving spring, the variation in speed of the mechanism during a given period may be made so small as to be negligible. The synchronized fly wheel 100 and attached gears and commutator will therefore be given a substantially uniform speed of rotation at a rate bearing a definite relation to the periodicity of the circuit breaker at the controlling device.

The speed of the apparatus may be any multiple or integral part of the rate of the periodic circuit breaker ii the apparatus is so designed, for even it contact block '78 makes contact with brushes 51 and 52 sevoral times during a period no action of the selecting relay will take place except at the moment when the circuit is closed at the clock. Since a motor of slow speed is large and costly it will be desirable to drive shaft 12 from motor 11 by gearing so that the motor may run at a suitable high sgeed.

In Fig. i there is shown the use of a single speed regulating device having two contact points to replace the pair of speed regulat- .ing devices shown in 1 and 2. This form of the apparatus consists of a weight 25 pivoted at 26, arm 2?, stop 29, contact screw 30 mounted in insulating block 31 and spring 32 similar to the parts of the mechanism previously described. IL contact spring mounted on an insulating block 91 carries a contact point SP2 interpo ed between arm 2? and contact screw 3 ll ire 83 leads from contact spring 90 to contact ring 3% and wire 33 from contact screw 30 to contact ring ill. \Vhen the 2- giiaratus is at rest contact point 92 is norn'ially not in contact either with arm 2'? or screw 30. l vhen the zqyparatus is started up and reaches a speed which the centrifugal force of weight will. overcome the force of spring 32 arm 27 will move toward and make contact with contact point 92 and speed has been chosen by the selecting mechanism so that contact point 92 is in the circuit of relay l the motor speed will at once be checked u the speed of the balance wheel. is reduced to point where spring can OVOiCODlG centrifugal force of wei ht 25 and move arm 2'? out of contact with contact point 92, thereby opening circuit 4-1 and reducing the speed of the motor. I however, the selecting apparatus has chosen the higher speed, contact point 92 will not be in circuit but contact screw 30 will be. The centrifugal force of weight will. now have to overcome the rcsi once of spring 32 as before but also ill have to bend spring 90 su'tlicientl to allow contact point 92 'to touch screw 30. This c1 work will require the ap mratus to run at a higher speed than before to produce the necessary centrifugal force, and the motor will be governed. accordingly.

An in'iportanituse of my device is in connection with the production of musical sounds in that class of instruments, such as the choral cello, wherein steel strings, supported, in connection with a sounding board, upon a piano plate, are Yllliil td by the ac tion of electrcinagnets, placed in j taposition thereto and periodically energized by an interrupted cu rent. in Fig. 1, a piano plate 80. carries steel string 81, and the sounding board String 81 hear at one end on a bridge oo, secured to sounding board 82, and upon a rail til at the other. and is stretched bet-ween pin 85 and tuning pin 86 in the usual manner. Mounted on a bracket 87 and opposite the string, but not in contact therewith, is a magnet 88. The circuit 89 of this magnet includes contact brush 69, commutator 22, the frame of the machine, a source of electric current 71 and a circuit breaker 90 operated by a piano key 91. The commutator 22 in this case consists of nearly equal segments of conducting and insulating materials, all the conducting segments being electrically joined to one another and to the frame of the machine. Now when the key 91 is pressed down and closes circuit breaker 90, a rapidly interrupted current is sent through the magnet 98, which periodically attracts and releases the string 81. If the periodicity of the interrupted current is the same as the rate of vibration of the string, it is thrown into vibrations sui'iicient for producing strong musical tones. As it is found that an extremely small difference between the periodicity of the current and the rate of vibraion of the string is sufficient not only to dcstroy the desired quality of the tone produced, but also to very greatly diminish the volume, it is essential that the speed of the commutator 22 shall be uniform and definite.

A shaft suitably supported in bearings 61 and 62 secured to base ll carries a pinion 63 which meshes with gear 21. Shaft 60 is splined and slidably mounted thereon is a friction wheel 64: which is keyed to shaft 60 so that wheel and shaft will rotate together. Wheel 6% is engaged by fork 65 attached to an adjusting rod 66 by means of which friction wheel 6 may be moved to any position along shaft 60. Friction wheel 6% touches and may be driven by a cone G7 rotatably mounted and arranged to be driven from any convenient source of power through a belt pulley 68. Gone 67 is in driving contact with wheel 6 in all positions of the latter along shaft 60 and obviously will impart to it and through it to gear 21 of the differential a speed of rotation varying in accordance to the position of wheel Every complete rotation of gear 21 will cause two rotations of bevel gear 20 and commutator 22 and if such rotation is accomplished while the synchrorotor is in operation, the rotation of the commutator resulting will be added to or subtracted from the rotations caused by the synchrorotor according to the relative direction of the respective motions.

The differential gear and the means for driving will also serve for changing the angular position of the commutator 22 where it is not desired to continuously add to or subtract from its rotations. This will be effected by turning shaft 60 by hand to the extent desired.

The circuit established through commu tator 22 and contact brush 69 may be used for any signaling purpose, such as telegraphy. Any or all of the bars of the commutator may be groundedon shaft 12 and such bars, shaft and the frame of the machine made parts of the signaling circuit. Other brushes contacting with commutator 22 may be added if other signaling circuits are desired. As an illustration we may as sume that all the commutator bars except one are completely insulated and that the remaining bar is grounded on shaft 12. Obviously once in each revolution of the commutator the circuit will be completed through the grounded commutator bar and brush and an impulse sent into the line. If more than one impulse per revolution is desired it is only necessary to connect other bars with the first.

The adjustment of the actual rotational speed afforded by the differential gear and the variable speed drive will be most desirable in synchronous telegraphy where it is desirable to keepin step commutators or kindred devices at distant points in order to accurately distribute among a number of local circuits at one point, the impulses sent from similar number of local circuits at another point and transmitted over a single line or by the methods of wireless telegraphy between the two points, as is done in the systems of Delane Rowland, and others. We will assume that synchrorotors are located at these points and that the controlling de vices are clocks having pendulums beating seconds and operating circuit breakers once per second. Even with the most accurate clock mechanism exact isochronism cannot be attained and a difference between the clocks of from one to five beats per day may be expected. As the number of beats of a seconds pendulum per day is 86,400 it will obviously be necessary at one point to add to or subtract from every 86,400 rotations of. the synchrorotor a number of rotations equal 7 to the difference between the beats of the two clocks per day. This will be accomplished and made synchronous by a suitable arrangement of the differential gear and variable speed drive.

My device may be modified in many struc tural respects. and by the substitution of mechanical. or electrical equivalents for any of the parts ofthe mechanism without thereby necessarily altering its essential operalion. Such modification will readily occur to those skilled in mechanic arts and I have not deemed it necessary to illustrate them here.

I claim as my invention the following:

1. In a synchrorotor the combination of a rotatively supported member, a spring of which one end is fastened to said member, and means for causing rotation of the other end of said spring at one or the other of two predetermined speeds, and mechanism for periodically selecting one or the other speed of rotation.

2. In a synchronizing apparatus the combination of a governed device including a' rotating member, a power driven shaft, and speed governing apparatus adapted to cause said shaft to revolve at one or the other of two predetermined speeds, with mechanism for periodically selecting one or the other of said two speeds for the rate at which said shaft shall revolve.

3. In a synchronizing apparatus, the combination of a governed device, comprising a rotating member, driving means therefor, and speed governing apparatus adapted to cause said driving means to run at one or the other of two predetermined speeds, with mechanism for selecting one or the other speed, and a controlling device adapted to periodically cause said mechanism to act.

eLIn a synchronizing apparatus a governeddevice comprising a rotating member, driving means therefor, two speed governing devices arranged to control said driving means and means for selecting one or the other device to control said driving means in combination with mechanism adapted to periodically cause said means to act.

5. In a synchronizing apparatus a governed device, comprising a rotating member, driving means therefor, speed regulating apparatus arranged to govern said driving means at two predetermined speeds and an electrically controlled means for periodically adjusting said apparatus to one or the other of said speeds. p

6. In a synchronizing ap'para'tusthe combination of a governed device comprising a revolving member, apparatus to be synchronized connected therewith, driving means,

speed regulating apparatus arranged to govern said means at either of two predetermined speeds, and means adapted to adjust said apparatus to one or the other of said speeds. with a controlling device for periodically ausing said means to act.

7. In a synchronizing apparatus the combination of a governed device comprising a revolving member, driving, means therefor, and speed regulating apparatus arranged to govern said driving means at two predetermined speeds, with time controlled means for ad usting said. apparatus to one or the other of said speeds in accordance with the angular position of said revolving member and a controlllng device for periodically causing said means to act.

'8. In a synchronizing apparatus the com-' 'bination of a governed device comprising a revolving member, driving means therefor, an elastic connection between said revolving member and said driving means, and speed regulating apparatus adapted to control said driving means at either one of two predetermined speeds, with. a device for electw an electrically controlled means for causing a selection to be made between said two speeds and a clock-operated circuit breaker in the circuit of said electrically-controlled means.

10. In a synchronizing apparatus the combination of a governed device, comprising a revolving member, driving means therefor, consisting of an electric motor, and speed regulating apparatus adapted to cause said motor to rotate at one of two predetermined speeds, said apparatus including means for varying the reslstance of a part of the motor clrcuit, with means for causing a selection of one of said two speeds to be made, and a device for periodically causing said means to act.

11. In a synchronizing apparatus the combination of a governed device comprising a rotating member, driving means therefor, and speed regulating apparatus adapted to cause said driving means to run at one of two predetermined speeds with an electrically operated speed selecting mechanism and a controlling device for periodically opening and closing the circuit of said mechanism.

12. In a synchronizing apparatus the combination of a governed device comprising a rotating member, driving means therefor, an elastic connection between said member and said driving means, and speed regulating apparatus adapted to cause said'driving means to run at one or the other of two predetermined speeds, with means for adjusting said apparatus to one or the other of said speeds in accordance with the angular position of said revolving member and clock-operated means for periodically causing said means to act.

13. In a synchronizing apparatus the combination of a governed device comprising a rotating member, a direct current electric motor having a shunt field winding, and a resistance in said shunt, and speed regulating apparatus adapted to cause said motor to run at one of two predetermined speeds and arranged to operate by opening and'closing a circuit around said resistance wlth means adapted to select one of the two speeds in accordance with the angular position of said revolving member at the time of selection' and a controlling device for periodically causing said selecting means to act.

14. In a synchrorotor the combination of a governed device including a rotating member. havin an aaratus to be s nehronized b 1.

attached thereto, a driving shaft, an elastic connection between said shaft and said rotating member, and speed regulating apparatus adapted to cause said shaft to revolve at one or the other of two predetermined speeds and selecting mechanism adapted to periodically determine at which speed said shaft shall revolve.

15. In a synchrorotor, the combination with an electric circuit and means for producing periodic interruptions therein of a governed device comprising a rotating member, driving means therefor, speed regulating apparatus adapted to cause said driving means to run at one or the other of two predetermined speeds, speed selecting means operated by said electric circuit, a mechanism to be synchronized, including two rotating parts and means for varying the relative rotative speed of said parts.

16. In a synchronizing apparatus the combination of a governed device including a rotatively supported member consisting of two parts, a spring of which one end is fastened to said member, means for rotating the other end of the spring at one or the other of two predetermined speeds and a variable speed mechanism for changing the relative speed of rotation of the parts of said member, with speed selecting mechanism and means for periodically causing a selection to be made.

17. In a synchronizing apparatus the combination of a governed device containing a rotating member, a contact sector attached thereto, driving means therefor, and speed governing apparatus adapted to cause said driving means to run at one or the other of two predetermined speeds, with mechanism for selecting one or the other of said speeds including two contact members arranged to touch. said contact sector at different angu' lar positions of said rotating member.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EDWARD G. THOMAS.

I'Vitnesses C. C. STENSON, J. WV. CULLY. 

